Boys can achieve higher grades at school if they are taught in single-sex classes, a British study shows.

The research, commissioned by ministers to stop boys falling further behind girls academically, found that male-only classes could help them to close the educational gap. Ministers are expected to use the findings — which will be released in the autumn — to encourage co-educational state schools to segregate the sexes.

At present, only a handful of co-educational schools teach boys and girls separately in Britain, and the practice is viewed with suspicion by many teachers, who often associate single-sex lessons with public schools.

However, ministers are determined to act as girls now outperform their male classmates at every level. They outscore boys in national tests at seven, 11 and 14, and also at at GCSE and A-level. In 2001, women also achieved more first-class university degrees than men for the first time.

Single-sex classes have been put forward as a solution because pupils in mixed-sex classes are more easily distracted by the opposite sex and can be too embarrassed to play an active part in the lesson.

Some commentators also claim that the predominance of coursework and the introduction of concepts such as “empathy” in history lessons are considered to be more suited to girls.

The government study, by academics at Homerton College, Cambridge, involved visits to primary and secondary schools where boys’ and girls’ results were rising so that they could identify which techniques boosted boys’ attainment.

The findings from four pilot secondary schools — one in rural East Anglia, one in an inner-city authority in the Northeast, one in a new town in the South and one in a northern town — showed that separating boys and girls aged 14-16 in subjects such as English rekindled boys’ interest and involvement.

The pilot summary said that using single-sex groups was a significant factor in establishing a school culture that would raise educational achievement.

Although there was conflicting evidence over the effects on examination results, the researchers found that where staff were committed and teaching was adapted to the boys, single-sex groups were successful.

Subsequent studies in the West Midlands found that the creation of temporary single-sex classes “has given increased confidence to both boys and girls”.

Grades improved, as did attendance rates and behaviour.

At Comberton Village College, in Cambridgeshire, 14-year-olds have been taught in single-sex English classes for five years to try to narrow the 20 per cent gap between boys and girls achieving GCSEs at grades A+ to C. Last year, that difference fell to about 5 per cent, compared with a national average of 17 per cent.

Mary Martin, the head teacher, said: “It became apparent very quickly that single-sex groups made for a more settled climate and classes that were more conducive to working. “The girls studied novels such as Jane Austen’s Pride and Prejudice, while the boys read works that would appeal to them more, such as Touching the Void by Joe Simpson, a first-person account of mountain survival. Martin is now considering creating single-sex classes in foreign languages.

Morley High School in Leeds, which has split the sexes in German and French for two years, has also seen boys’ results improve. All are now achieving at least a grade D at GCSE, compared with a third of boys three years ago.

Michael Younger, one of the directors of the research, said: “In two or three schools, single-sex teaching is working very well. In one school where staff are less committed, it is not. However, where the idea has been sold to staff, pupils and parents, and developed, there is the probability that it will transform results.”

Younger said at Kings’ School in Winchester, which is taking part in the study, boys’ English and foreign language grades had shown a marked improvement in the single-sex classes.

“If we could replicate those conditions in other schools, it would make a real difference to boys’ underachievement.”

Not all schools, however, are convinced. Many oppose the move as a retrograde step that threatens the notion that mixed schooling is best.

David Hart, the general secretary of the National Association of Head Teachers, said that segregating the sexes should not be seen as a panacea.

He said: “Evidence is emerging that it can work in some subjects but whether many schools will go down that route is a different question.

“Most heads think that if it is a mixed school, young people are taught together. If schools depart from that philosophy widely, it would have to be underpinned by very compelling evidence.”